Police in the UK say there is "nothing to suggest" Novichok caused two people to fall ill at a restaurant in Salisbury, England, on Sunday.
Earlier they declared a major incident and sealed off the restaurant and the surrounding roads.
Police were called by the ambulance service to the Italian restaurant Prezzo at 6.45pm local time following a "medical incident" involving a man and a woman.
The pair were taken to hospital amid suggestions they had been exposed to an unknown substance.
The "medical incident" was reported in the same city where former Russian agent Sergei Skripal and his daughter Yulia were poisoned in March.
Prezzo is just a few hundred metres from the Zizzi restaurant where the Skripals ate before they collapsed.
Britain has said Russian officers used the nerve agent Novichok to attack the Skripals. The Kremlin has denied any involvement.
But police later said there was no evidence Novichok was behind the latest illnesses. The pair were kept in hospital for observation, while enquiries continued into whether a crime had been committed.
Earlier, BBC journalist Emma Volney tweeted that four ambulances were sent to the area, including a hazardous response team.
"The patients were conscious when emergency services arrived and were being treated at the scene," she wrote.